4. A firm that produces handbags is incurring total costs of production in the short run of $31,200 per day. The firm's average variable cost equals $40 per unit and its average fixed cost equals $80 per unit. Complete parts (a) through (c) below. a. How many units is the firm producing per day? 260 u n its b. What are the firm's total variable costs at this output level? $ 10,400 per day 0. What are the firm's total fixed costs at this output level? 5 20,800 per day